(b) The county commission of a county with a municipal planning commission may, by ordinance, designate the municipal planning commission as the county planning commission. A municipal planning commission designated as a county planning commission has all the powers, authority and duties granted under this article to a county planning commission.
(c) If a municipality is located in more than one county, this section only applies to the county where the major portion of the territory of the municipality is located.
(d) Municipalities and counties may contract annually with each other to pay expenses for shared planning commissions.